This disclosure relates to a gas turbine exhaust component and a method of manufacturing the same.
Some gas turbine engines, in particular military turbojet engines, utilize exhaust nozzles having nonsymmetrical contours. That is, the exhaust nozzle is not symmetrical about at least one plane within which the longitudinal axis of the exhaust nozzle lies. Generally, exhaust nozzles are arranged downstream from augmentor ducts in some military turbojets. These types of exhaust nozzles are expensive to manufacture, but the cost is spread over a relatively large number of productions units. On the other hand, in some demonstrator engines, exhaust nozzles are manufactured in low volumes. The low manufacturing volumes of demonstrator engines, particularly those with non-symmetrical contours, make it difficult to provide exhaust nozzles in a cost effective manner.
Generally, exhaust nozzles for demonstrators are fabricated from sections of aerospace material such as, but not limited to, titanium or nickel that are welded together. These sections are generally fabricated using tools such as forming tools used in high volume production. These types of fabrication tools may generally cost up to several million dollars, resulting in very large non-reoccurring expenditures for the tooling, welding, weld fixtures and post-weld heat treat and stress relief, and weld inspection. Because the exhaust nozzles for demonstrators are generally amortized over one or two sets of engine hardware, the non-reoccurring expenditures are costly relative to the amount of fabrication making it difficult to obtain competitive work for a demonstrator or technology program where cost is a considered as significant factor.
The fabricated and/or welded sections are generally secured by welding the sections to prefabricated circumferential ribs that are arranged at the exterior of the sections. Due to distortions from welding, inner surfaces of the circumferential ribs are generally subjected to additional grinding or machining to fit or accommodate the longitudinal sections. This additional fitting adds further labor and cost to the exhaust nozzles. What is needed is a lower cost exhaust nozzle manufacturing method capable of producing non-symmetrical exhaust nozzle contours.